If they ARE seed-bearing variety, and you want to let them mature to seed (which is really a lot of fun for the kids to see the progression and full circle from seed-to-seed), and, also, if you plan to possibly eat them (very nutritious), some people recommend covering them with tulle netting to keep out the bugs that eat the seeds once they have been pollinated and the petals start to shrivel.
Sometimes, the grubs only get the peripheral seeds but sometimes they tunnel from one seed to another and do quite a bit of damage.
I cut the flower heads off once the back of the flowers turn yellow because after that, they're prone to getting moldy in my area if left outside. I pre-process by removing all dried petals and also most of the triangular bracts (you can catch the grubs in the peripheral seeds at this time too). I leave a long stem attached and use it to hang them from the ceiling (actually I used curtain rods) with a kitchen twine or string until they are fully dried.
You can eat the seeds or use them in birdfeeders. You could also make winter suet/dough/peanut butter ball with the sunflower seeds mixed in. You can get a lot more mileage from those sunflower seeds you and your daughter planted back in spring.